This study, based on comparative morphology reinforced by phylogenetic relationships deduced from matK sequences, records 15 species in three genera of Podostemaceae subfamily Tristichoideae from Laos. The species new to science are Dalzellia attapeuensis, D. microphylla, D. pseudoangustissima, Terniopsis microstigma, T. savannaketensis, T. sesadensis, and T. vapyensis. Cussetia diversifolia is excluded from the flora, although it has been reported as being in Laos. Floristic comparison by country shows a significant overlap between the Lao and Thai floras. Given not only the large number of species but also the high incidence of endemism, where seven of the 15 species are known only from within the country, Laos, together with Thailand, represents a center of diversity for Tristichoideae in Asia.

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Although there have been several studies on the phylogeny of Impatiens, no such studies have focused on Impatiens in Sumatra. This study aimed to reveal the phylogeny of Sumatran Impatiens and evaluate their position among species from other regions. The atpB-rbcL intergenic spacer from plastid DNA and the Internal Transcribed Spacer region from nuclear ribosomal DNA (1414 bp in total) was sequenced for 24 samples representing 18 species of Impatiens, including 16 species endemic to Sumatra. Parsimony analyses were done with the addition of outgroups and sequences of Impatiens from the NCBI GenBank. According to the strict consensus of 2120 most parsimonious trees from the combined data set, Impatiens is monophyletic with 93% bootstrap support. The ITS and atpB-rbcL data showed that Sumatran Impatiens is distributed in more than one clade depicting multiple origins from southern China. The addition of Sumatra-endemic species indicates that Impatiens probably originated in southern China.

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A new species of Bignoniaceae, Stereospermum binhchauensis, recently discovered in the Binh Chau - Phuoc Buu Nature Reserve of southern Viet Nam, is described and illustrated. Stereospermum binhchauensis is morphologically similar to S. neuranthum Kurz, but differs in having a longer inflorescence, 30-45 cm long and a yellowish purple, pubescent, longer corolla, 4-5 cm long. A key to the species of Stereospermum in Viet Nam is also provided.

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Thirteen new species from Bokor National Park, Kampot Province, Cambodia are described and illustrated: Heteropanax bokorensis Tagane & Nagam., sp. nov., Schefflera cambodiana Yahara & Tagane, sp. nov., Dichapetalum cambodianum Tagane & Nagam., sp. nov., Elaeocarpus bokorensis Tagane, sp. nov., Croton phourinii H. Toyama & Tagane, sp. nov., Lithocarpus eriobotryifolius Yahara, sp. nov., Cinnamomum bokorense Tagane & Yahara, sp. nov., Cinnamomum dimorphandrum Yahara & Tagane, sp. nov., Lindera bokorensis Tagane & Yahara, sp. nov., Memecylon bokorensis Tagane, sp. nov., Syzygium elephantinum Tagane, sp. nov., Phyllanthus bokorensis Tagane, sp. nov., and Ardisia smaragdinoides Yahara & Tagane, sp. nov. In addition, Rhaphiolepis mekongensis (Cardot) Tagane & H. Toyama, stat. nov. is recognized as a distinct species. A lectotype for R. indica var. mekongensis Cardot is also selected.

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